At the time of each restart of a ring-spinning or ring-twisting thread making machine, normally strand breakage occurs intermittently and, to be sure, occurs with the ring-spinning machine more frequently than with the ring-twisting machine.
It is a known, empirically recognized fact that the number of strand breaks, happening when such a machine is restarted from a standstill during the acceleration period, are essentially greater if the ring rail or rails are moved upwards at the moment of restart by the spinning or threading machine.
The thread-break count is substantially smaller if the ring rail or rails move at the time of restart toward a lower position.
It is therefore common in such ring-spinning machines, if the machine is stopped to exchange an empty bobbin for a full bobbin, to lift the ring rail or rails from their random position at the moment of stoppage to one which is half the height of the bobbins and to move them first on restart of the machine in the downward direction.
However, stoppage of such a ring-spinning or ring-twisting machine, when occurring other than for exchange of bobbins, is usually due to an interference even which interrupts the normal wind-up of the strands.
Such latter-type stoppages may occur through manual or automatic emergency switch-off or power failure. After elimination of the interference causing the emergency shutdown or power failure, the machine resumes the thread winding on the bobbins without the aforementioned spool changes.
It is therefore inevitable that the machine, upon such resumption, restarts the ring rail in the same operating direction that it had at the cessation of its operation, so that the ring rail frequently runs in the upward sense with resultant higher strand-breaking count.